Continuous production of antibacterial carboxymethyl chitosan-zinc supramolecular hydrogel fiber using a double-syringe injection device
Introduction
Over the past several decades antibacterial hydrogels (ABHs) had received a great deal of research interest because of their superior relevance to numerous biomedical applications, such as wound dressing, drug delivery and tissue engineering [[1], [2], [3], [4]]. Traditional method to prepare ABHs falls into two categories: 1) chemical conjugation or physical loading of antibacterial agents (e.g., antibiotics, silver nanoparticles, bactericidal peptides, etc.) onto a conventional hydrogel network [[5], [6], [7]]; 2) direct cross-linking of certain cationic polymers, which exhibit intrinsic contact-killing property to bacterium [[8], [9], [10]]. However, the synthesis of bactericidal peptides/polyelectrolytes still suffers from low product yield and most conventional synthetic polymers exhibit poor biocompatibility, thus limiting their wide application in biomedical field. Therefore, despite of extensive studies on ABHs, it is still highly desirable to develop a robust and controllable strategy for large-scale production of ABHs with a biocompatible material.
In contrast to synthetic polymers, biopolymers from natural resource usually exhibit good biocompatibility, biodegradability, availability and renewability. Therefore, extensive efforts had been placed on the development of ABHs using biopolymers (e.g., cellulose, alginate, chitosan, etc.) [[11], [12], [13], [14], [15]]. Of particular interest, chitosan and its derivatives exhibit intrinsic antibacterial property due to their polycationic nature, making them potentially useful for numerous biomedical applications [[16], [17], [18], [19]]. Carboxymethyl chitosan (CMCh) is an important derivative of chitosan and can be easily obtained by treating a commercial chitosan with monochloroacetic acid in an alkaline medium [20]. When compared with pristine chitosan, CMCh was reported to have better biocompatibility, biodegradability, as well as enhanced antioxidant activity [[21], [22], [23], [24]]. Consequently, CMCh had been used as biomaterials in various biomedical fields [[25], [26], [27]].
Our group previously reported a facile method for the preparation of CMCh-metal ion (e.g., Ag+, Cu2+ and Zn2+) supramolecular hydrogel by simply mixing a CMCh solution with a metal ion solution at an appropriate pH value, and the resultant hydrogels exhibited excellent antibacterial activity [28]. Considering the fact that topical administration of Zn2+ is beneficial for wound healing process [[29], [30], [31]] and have a lower cytotoxicity than Cu2+ [32], the CMCh-Zn supramolecular hydrogel is believed to be highly promising as wound dressing material. However, it should be noted that the gelation process of CMCh-Zn hydrogel is very fast (i.e., usually within a few of seconds especially when using a high concentration of Zn2+ solution) [28,33], making it difficult to obtain a homogeneous hydrogel on a large scale by simply mixing CMCh with Zn2+ solution. Thus, the objective of the current project is to develop a suitable device and strategy for the continuous production of antibacterial CMCh-Zn supramolecular hydrogel.
According to the literature, both microfluidic injection and in-line mixing techniques allow for continuous production of biopolymer-based nano/micro structures, including nanoparticle, microcapsule, as well as, microfiber [[34], [35], [36], [37], [38], [39], [40], [41]]. For instance, alginate supramolecular hydrogel fibers, which were prepared by using different microfluidic devices, had been extensively studied for biomedical applications, such as localized delivery of therapeutics, tissue remedy at specific position and 3D culturing of cells [[42], [43], [44], [45], [46], [47], [48]]. However, most reported microfluidic devices themselves rely on sophisticated fabrication process and thus are not suitable for large-scale production of ABHs.
In order to reduce both the complexity and the cost of a microfluidic device, in this work, a double-syringe injection device was designed and built using a syringe-pump and some Luer-Lok fittings and polypropylene tubings. Then, the flow rates of both CMCh and Zn2+ solution were optimized for the continuous production of homogeneous CMCh-Zn hydrogel fiber. The loading of Zn2+ into the CMCh-Zn hydrogel fibers was controlled by adjusting the Zn2+ concentration, and then determined by inductively coupled plasma atomic emission spectrometer (ICP-AES). Both the surface and inner morphologies of the CMCh-Zn hydrogel fibers were examined by using scanning electron microscope (SEM). At last, antibacterial activities of the CMCh-Zn hydrogel fibers against both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) were investigated via inhibition zone method.
Section snippets
Materials
Chitosan with a molecular weight of ca. 20 kDa and a deacetylation degree of ca. 90% was obtained from Weifang Sea Source Biological Product Co., Ltd. (Shandong, China). Monochloroacetic acid was purchased from Macklin Biochemical Co., Ltd. (Shanghai, China). Yeast extract and Tryptone were obtained from Oxoid Ltd. (U.K.). Agar powder was provided by Solarbio Science and Technology Co., Ltd. All other chemicals like zinc nitrate hexahydrate (Zn(NO3)2·6H2O), sodium hydroxide and acetic acid were
Influence of total flow rate
Firstly, we compared the CMCh-Zn hydrogel fiber prepared at different total flow rate (i.e., the sum of both CMCh and Zn2+ solutions). Fig. 2 gives the photographs of a series of hydrogel fibers prepared at different total flow rates ranging from 13.5 mL/min to 135 mL/min. Noted that a slower flow rate than 13.5 mL/min (i.e., the flow rates of CMCh and Zn2+ solution are 10.5 mL/min and 3 mL/min, respectively) would result in the clogging of glass tube outlet. On the other hand, for 1.5 M of Zn2+
Conclusions
In this work we demonstrated the construction of a double-syringe injection device using all the commercial parts, which allowed for continuous and controlled production of antibacterial CMCh-Zn supramolecular hydrogel fibers. Homogeneous fibers with a high loading of Zn2+ could be easily achieved by increasing the Zn2+ concentration up to 2.0 M. The resultant CMCh-Zn supramolecular hydrogel fibers exhibited good stretchability, knittability and a 3D microporous architecture with a relatively
Author statement
Yu-Long Wang: Investigation, Methodology. Ya-Ning Zhou: Investigation, Methodology. Xin-Yu Li: Investigation, Validation. Ju Huang: Investigation, Validation. Fazli Wahid: Investigation, Methodology. Cheng Zhong: Supervision. Li-Qiang Chu: Conceptualization, Supervision, Writing- Reviewing and Editing.
References (52)
- et al.
Hydrogel wound dressings for bioactive treatment of acute and chronic wounds
Eur. Polym. J.
(2018) - et al.
Dual function injectable hydrogel for controlled release of antibiotic and local antibacterial therapy
Biomacromolecules
(2018) - et al.
Injectable antibacterial conductive hydrogels with dual response to an electric field and pH for localized “smart” drug release
Acta Biomater.
(2018) - et al.
Reusable ternary PVA films containing bacterial cellulose fibers and ε-polylysine with improved mechanical and antibacterial properties
Colloids Surf. B: Biointerfaces
(2019) - et al.
Biopolymer-based functional composites for medical applications
Prog. Polym. Sci.
(2017) - et al.
Injectable polysaccharide hydrogel embedded with hydroxyapatite and calcium carbonate for drug delivery and bone tissue engineering
Int. J. Biol. Macromol.
(2018) - et al.
Chitosan as an environment friendly biomaterial – a review on recent modifications and applications
Int. J. Biol. Macromol.
(2020) - et al.
Chitosan as biomaterial in drug delivery and tissue engineering
Int. J. Biol. Macromol.
(2018) - et al.
Cinnamyl O-amine functionalized chitosan as a new excipient in direct compressed tablets with improved drug delivery
Int. J. Biol. Macromol.
(2019) - et al.
Recent advances on chitosan-based micro- and nanoparticles in drug delivery
J. Control. Release
(2004)
Chemical characteristics of O-carboxymethyl chitosans related to the preparation conditions
Carbohydr. Polym.
The implications of recent advances in carboxymethyl chitosan based targeted drug delivery and tissue engineering applications
J. Control. Release
O-carboxymethyl functionalization of chitosan: complexation and adsorption of Cd (II) and Cr (VI) as heavy metal pollutant ions
React. Funct. Polym.
A novel pH-sensitive hydrogel composed of N,O-carboxymethyl chitosan and alginate cross-linked by genipin for protein drug delivery
J. Control. Release
Interactions of metal ions with chitosan-based sorbents: a review
Sep. Purif. Technol.
Biomedical applications of carboxymethyl chitosans
Carbohydr. Polym.
Novel carboxymethyl derivatives of chitin and chitosan materials and their biomedical applications
Prog. Mater. Sci.
Efficient water soluble O-carboxymethyl chitosan nanocarrier for the delivery of curcumin to cancer cells
Carbohydr. Polym.
Facile fabrication of moldable antibacterial carboxymethyl chitosan supramolecular hydrogels cross-linked by metal ions complexation
Carbohydr. Polym.
Enhanced antibacterial and wound healing activities of microporous chitosan-Ag/ZnO composite dressing
Carbohydr. Polym.
Tuning physicochemical and biological properties of chitosan through complexation with transition metal ions
Int. J. Biol. Macromol.
Injectable self-healing carboxymethyl chitosan-zinc supramolecular hydrogels and their antibacterial activity
Int. J. Biol. Macromol.
Automated in-line mixing system for large scale production of chitosan-based polyplexes
J. Colloid Interface Sci.
Static mixers in the process industries—a review
Chem. Eng. Res. Des.
Electrospinning versus microfluidic spinning of functional fibers for biomedical applications
Biomaterials
Self-crosslinking effect of chitosan and gelatin on alginate based hydrogels: injectable in situ forming scaffolds
Mater. Sci. Eng. C Mater. Biol. Appl.
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